Ước lượng mờ trạng thái hệ thống phi tuyến. doc

Tep chi Tin hoc va Dieu khien hoc, T.20, S.4 (:?004), 351-354 I' " , A lJOC LlJQ'NG MO TRI;\NG THAI H~ PHI TUYEN VU NHU LAN, VU CHAN HUNG, vA DANG THANH PHU Vifn Gong nghf thOng tin Abstract. The authors have proposed a fuzzy filtering scheme with the asumption that the mem- bership functions are triangular. The nature of the proposed method in this article ifi.using fuzzy logic to find the nonlinear function in the problems of estimating system state. This method is much more simple than the other ones such as [1,2,3]. Tom t~t. M9t hroc do 19C mo diroc de xujit voi gici thiet rang ham thuoc co dang tam giac, Ban chat cua phuang phap de xuat la su dung logic mo tim ham phi tuyen trong bai toan iroc hrcng trang thai he thong. Phuang phap nay don gian han so voi nhieu phuang phap khac nhir [1,2,3]. C6 the trinh bay t6m tiit bai toan iroc hrcng trang thai kinh dien nlnr sau. Xet h~ phi tuyen: Xn+l = f(xn) + Wn, (la) Zn = h(xn) + V n , (lb) trong do vecta Xn - trang thai h~ thong a thai diem n, Wn - nhieu triing chuan, Zn - vecta quan sat, Vn - nhieu quan sat, f(.) va h(.) la cac vecta ham phi tuyen cua trang thai. Gia thiet rKng cac ki vong: E(xo) = xo, (2) E[(xo - xO)lT = Po, (3) E[wnl = E[(vn)l = 0, \In, (4) E[w n vTJ = QO'nl, (5) [vn vTl = RO'nl· (6) B9 19C Kalman mo rong cho phep tim dircc uoc hrong Xn+l cua trang thai Xn+l trim co sa cac quan sat Zn (n = 0,1,2, ). Neu tinh phi tuyen a h~ (1) du trori thi c6 the khai trien (1) xung quanh trang thai nhir sau: f(xn) ~ f(xn) + 8~~) Ix=xn (xn - xn), (7a) h(xn) ~ h(xn) + 8h;;X) Ix=xn (xn - xn). (7b) Tir d6 c6 the viet (1) d iroi dang: Xn = f(Xn-l + Kn[zn - h( -Xn+l)], (8a) Cho h~ (1), iroc hrong tim diroc co the viet duoi dang tong quat: Xk = j(Xk-l) + 9(Zk' Xk-l). (9) 352 vO NHU LAN, vO CHAN HUNG, V A DANG THANH PHU «; = PnHn(Rn + H~ PnHn)-l, P; = Fn(P n - l - KnH~ Pn-dF',[ + Qn, (8b) (8c) voi Fn = f(xn) va Hn = h(xn). Nhtr v~y iroc hrorig thu duoc chi la gan dung. Dieu nay gQ'i mo cho viec su dung logic mo. Nhieu tac gici da su dung kha nang nay [1,2,3]' tuy nhien diro i day se trmh bay mot phuong phap hoan toan khac, don gian ho'n va de su dung hen. 2. D~T BAI TOA.N U<1C LUQ'NG MO , a day g(.) chinh la ham mo tci sir sai lech giira tree hrong tirn diroc va trang thai chinh xac cua he (1). Co the noi rKng khcng co mot pmrcng phap nao tir trtroc den nay cho phep xac dinh chinh xac ham nay. Nhir vay co the coi g(.) la ham mo. Tir day, gicii phap cho van de neu tren la su dvng logic mer tim ham g(.) theo quan diem [4l. 3. GIAI QUYET BAI TOA.N U<1C LUONG MO Cau true bo iroc lirong me diroc the hien nhir sau. Ucc hrong 19C: Xk/k = Xk/k-l + gl(Zk,Xk/k-d· (lOa) U'oc hrong dtr bao: Xk/k-l = Xk-l/k-l + g2(Zk-l, Xk-l/k-l), k = 1,2, gi = [gil,gi2, ,ginl T , girc[minir,maxirlcR, r=I,2, :,n, i=I,2, vo i dieu ki~n ban dau: (lOb) XO/O = :ro· Cac vecto ham gl (.), g2 (.) co 2 vecto dau vao el, .6el va e2, .6e2 ttro ng irng va tai thai diem k co: elk = Zk - h(Xk/k-d, .6elk = elk - el(k-l), e2(k-2) = Zk-l - h(Xk-l/k-l), .6e2(k-l) = e2(k-l) - e2(k-2), (lla) (llb) (12a) (12b) voi: eik = [eikl' eik2,· , eikml T , .6eik = [.6eikl' .6eik2,· , .6eikml T , eikp C [min eikp, max eikpl C R, .6eikp C [.6 min eikp,.6 max eikpl C R, p = 1,2, ,m. u6c LUQNG MO TRANG THAI HI;; PHI TUYEN 353 Gia Slr r~ng ca sa luat mo mo ta quan he giira cac sai s6 eikp, /:).eikp va glr(.), g2r(.) diroc cho tai bang 1 va bang 2 theo dinh huang cua tri thirc chuyen gia duo i dang ngon ngir tv nhien: qua nho, tilu), hcri nh», truno binh, hcri tun, tun, qua tun. Dau ra glr(.) va g2r(.) la 5 tap mo va 7 tap mo tirong irng cling dirci dang ngon ngir tv nhien nhir tren (xem bang 1 va bang 2). Phan b6 cac t~p mo tai dau vao va dau ra gia thiet la deu nhau (chua xet den bai toan t6i iru tham s6 ham thuoc). Bdng 1. Co sa luat cho glr(.) tai thai diem k /:).eIp(k) qua nho nh6 trung binh Ian qua Ian qua nho qua nho qua nho nhO nh6 trung binh eIp(k) nhO qua nho nhO nh6 trung binh Ian trung binh nh6 nh6 trung binh Ian Ian Ian nho trung binh Ian Ian qua Ian qua Ian trung binh Ian Ian qua Ian qua Ian Bdng 2. Co sa luat cho g2r(.) tai thai diem (k -1) /:).e2p(k - 1) qua nh6 ho i trung hoi Ian qua nh6 nhO binh Ian Ian qua qua qua nhO nhO ho i ho i trung nhO nhO nhO nhO nhO binh nhO qua nhO nhO hoi ho i trung ho i nhO nh6 nh6 binh Ian hai nhO nhO ho i hai trung hoi ho i e2p(k - 1) nho nhO nhO binh Ian Ian trung nhO hoi ho i trung ho i hoi Ian binh nh6 nh6 binh Ian Ian hai ho i hoi trung hoi hai Ian Ian .km nh6 nh6 binh Ian Ian Ian hoi trung hoi hoi Ian Ian qua nhO binh Ian Ian Ian qua trung ho i ho i Ian Ian qua qua Ian binh Ian Ian Ian Ian Ham thuoc d6i voi glr(.) va g2r(.) nen Slr dung tam giac de tinh toan don gian. Nhir vay co the dinh nghia ham thuoc voi 3 tham s6 (II j , CL, rI j ) cua dau vao j (j = 1,2), (i = 1,2,3,4,5) d6i voi glr(.) va (lZj' Cf j , rh) cua dau vao j (j = 1,2), (i = 1,2,3,4,5,6,7) d6i vo i g2r(.). Ham thuoc co dang: { (_ C )/1" 1 + X 2Jr 2Jr f-Lijr(X) = 1 - (x - Cijr)/rijr o (; day: x ~ eikr hoac /:).eikr neu -lijr::; (x - C ijr ) ::; 0, neu 0::; (x - C ijr ) ::; rijr, cac trirong ho p can 10i. (13) 7 0 ) 0 L !-Li2r(Yi2r Yi2r i=l ( Xk 11k-I) = 7 ( 0 ) 92r Zk-l, - L !-Li2r Yi2r i=l (15) 354 vO NHlJ LAN, vO CHAN HlJNG, vA BANG THANH PHU D~u ra 91r (.) sau phep giai mo theo phirong phap trong tam co dang: 5 L !-Lilr(Y?lr)Y?lr 91r(ZkXklk-l) = -i=-1-::-5 L !-Lilr(Y?lr) i=l (14) veri Y?lr - trong tam tap mo dau ra tlnr i cua glr(.), Y?2r - trong tam tap mo dau ra thir i cua 92r(.), va !-Lilr(Y?lr) = sUP{!-Lelr(e~kp) A !-LLlelkpr(~e~kp)}, !-Li2r(Y?2r) = SUp {!-Le2 r (egkp) A !-LLle2kpr(~egkp)}· V eri t~p dau vao ro tinh diroc truce: elkp = e~kp , ~elkp = ~e~kp ; (18) e2kp = egkp , ~e2kp = ~egkp· (19) Nhir v~y da xac dinh diroc iroc IUQ'ng trang thai tai cac thai diem k theo (10), (14) va (15). Liru y rKng trong tnrorig hop e va ~e qua Ion co the phat trien them phan t6i tru h6a tham s6 ham thuoc. Phan nay se diroc tiep tuc xem xet them trong tirong lai. (16) (17) 4. KET LUAN Bai bao da ae xuat each giai quyet tuang d6i don gian bai toan iroc hrcng trang thai h~ phi tuyen dua tren ca sa logic mo. Giai phap nay khac hiin veri cac giai phap [1,2,3]. Phuong phap tren con co the S11 dung khi nhieu w(n) va v(n) trong mo hinh (1) khong phai la trang chuan. Truong hop nay cac phuong phap iroc IUQ'ngkinh dien khong giai quyet diroc. TAl Ll:¢U THAM KHAO [1] Fernandez S. A., Lopez C. A., and Alzola J. R., A fuzzy-controlled Kalman filter applied to stereo-visual tracking schemes, Signal Processing 83 (2003) 101-120. [2] Kobayeshi K., Cheok K., and Watenable K., Estimation of the absolute vehicule speed using fuzzy logic rule-based Kalman filter, American Control Conj., Seattle, 1985, 3086- 3090. [3] Simon D., Fuzzy estimation of DC motor winding currents, North American Fuzzy Infor- mation Processing Society Conj., NewYork, 1999, 859-863. [4] VU Nhir Lan, VU Chan Hung, va Dang Thanh Phu, Phuong phap mci mo hinh mo h~ dong h9C chira bat dinh, Top chi Khoa h9C va Cong ngh~ 40 (so DB) (2002) 115-110. Nluin bdi ngay 10- 12 - 2003 . S.4 (:?004), 351-354 I' " , A lJOC LlJQ'NG MO TRI;NG THAI H~ PHI TUYEN VU NHU LAN, VU CHAN HUNG, vA DANG THANH PHU Vifn Gong nghf thOng tin Abstract. The. dang tam giac, Ban chat cua phuang phap de xuat la su dung logic mo tim ham phi tuyen trong bai toan iroc hrcng trang thai he thong. Phuang phap nay don